.NET API PostToAnnotationRelationForDocumentAnnotations

Hi,

I want to add annotation to a document from another application using .NET API, I used the code from this page:
https://developer.docuware.com/dotNet_CodeExamples/7c924cf7-b658-454f-924f-0dd83305bb14.html

When calling:

page.PostToAnnotationRelationForAnnotation(annotations);

I get this error:
ArgumentException: The specified link is not found. Make sure that you are using the complete resource.(You can get the complete resource by getting it from the SelfRelation)

I see that some resource of the document are null including AnnotationRelationLink, how  can I get the complete resource?

Regards

Ameen

Problem solved by calling:

document = document.GetDocumentFromSelfRelation();

Before posting the annotation.